We want to set different rules for purchase order approval based on total amount.
If amount of PO for (Spare Part) is less than INR 50,000, approval from GM is not required. Approval required only from Finance Manager.
If amount of PO is greater than INR 50,000, so first approval from finance manager & second approval from GM
You can set approval slabs on each purchase order type. Slabs correspond to net total values. For each slab you can specify a different approval rule. Since you have mentioned only one threshold, which is 50,000, please go to purchase order management and edit the type of purchase order. Add a slab with value 50,000. Next to the slab value there is a dropdown to select the approval rule. Use that to specify the rule for this slab. You would have already selected another rule on top for base order (value less than lowest slab). You will have two rules, one when value is less than 50,000 and other when value is 50,000 or more.
You can create and configure these rules in advance.
Please note that the slab values are specified in your local currency, which in your case is INR. For other currencies system will auto-calculate values based on exchange rates at the time of creating the purchase order.